The Memorial Sloan-Kettering Cancer Center (MSKCC) is seeking $15 M of federal support for a $19.74 M project to expand and equip an existing state-of-the-art barrier vivarium. As a result of weakening economic conditions, MSKCC was forced to cease construction on the second phase of a laboratory research building so a much-needed animal facility expansion was not completed. This decision, although clearly necessary to ensure the Center's financial stability, has left MSKCC with insufficient vivarium space. This project is vital to the center's growing research enterprise for a number of reasons. First, the development, characterization, and use of animal models, particularly mouse models, are critical to our research efforts aimed at understanding and controlling cancer. Second, the utilization of mice by MSKCC researchers has grown dramatically over the last decade, due to new faculty recruitments and the development of powerful technologies for manipulating the mouse genome to alter the expression of oncogenes and tumor suppressors. MSKCC has now reached the point where ongoing research will be limited by the available animal space. Finally, MSKCC is in the midst of a major expansion of its laboratory research programs. The principal goal of this expansion is to strengthen the interface between basic and clinical science by recruiting investigators, including physician-scientists, who are interested in translational cancer research. Since these investigators will clearly make extensive use of animal models, continued faculty recruitment at MSKCC is critically dependent upon the development of additional animal space. The project entails expanding an existing vivarium by fitting out the cellar and associated interstitial/mechanical space of a contiguous building. The highly efficient (72% net/gross) expansion will provide an additional 31 small animal holding rooms and 13 animal procedure laboratories. When complete, the expansion will provide an additional 23,450 individually ventilated mouse cages, with the capacity to house approximately 100,000 mice. Funding is also requested to purchase high density individually ventilated caging systems (IVCS);vertical flow changing stations;biological safety cabinets;and specialized IVCS designed for safe and efficient rodent CO2 euthanasia. The requested funds will be used entirely in support of American jobs. Approximately 20,000 worker days will be created by construction and equipment purchase. Seven thousand two hundred fifty worker days per year will be required to staff the vivarium when fully occupied. Sustainable design and construction methods are key components of the project. MSKCC anticipates obtaining LEED silver certification upon building completion.